Low-permeability sandstone reservoirs with low clay content are prone to water-sensitive damage during the fracturing process. In field applications, serious formation damage occurred with the conventional fracturing fluid system using KCl clay stabilizer. The introduction of SP clay stabilizer into the fracturing fluid formulation system significantly reduced the water-sensitive damage during fracturing and improved the reservoir transformation and production enhancement effect. In this paper, the clay stabilization mechanism of two substances, inorganic clay stabilizer KCl and organic ammonium salts with low molar weight SP, is studied by tests of swelling inhibition, zeta-potential test, and scanning electron microscope test to compare. On this basis, the adsorption behavior of SP on the surface of clay minerals is also studied in depth by isothermal adsorption and desorption experiments to explain mechanistically the difference of two different clay stabilizers on the fracturing effect, which helps to solve the formation damage problem in the fracturing and production enhancement process of low-permeability sandstone reservoirs with low clay content.

This study investigates the application of carbon quantum dots as tracers in inter-well connectivity monitoring. A new laboratory-made water-soluble carbon quantum dot fluorescent tracer (CQD-W) was studied using 3D fluorescence characterization, structural characterization, reservoir suitability evaluation, and core flow experiments. The experimental results showed that CQD-W has a size of about 2 nm, a minimum detection limit of 10−2 mg·L−1. It has good stability when the salinity is 200,000 mg·L−1, the concentration of Ca2+ is 1000 mg·L−1, the pH value is 1–9, and the temperature is 80 °C. Because CQD-W contains many functional groups, such as carboxyl and hydroxyl, it shows good water solubility and has a negative surface charge. In the process of formation flow, CQD-W has a small adsorption amount, high tracer resolution, and excellent injectivity and mobility, meaning it is less likely to cause reservoir damage. Through the study of this method, the application field of carbon quantum dots is broadened, and it is proved that the CQD-W fluorescent tracer has a high potential for application in the oil industry, laying the foundation for the popularization of this technology.

纳米二氧化硅是目前应用最为广泛的一种纳米材料,但其团聚行为对粒径测量和应用效果有不利的影响.为减少纳米二氧化硅颗粒的团聚行为,应用动态光散射粒度分析方法,考察了分散方式、分散剂种类、悬浮液条件对不同纳米二氧化硅的粒径及多分散性指数(PDI)的影响规律.实验结果表明,磁力搅拌条件下,0.1％(质量分数)的PEG-2000对各类纳米二氧化硅均具有较好的分散效果;随着悬浮液pH增大,硅溶胶悬浮液粒径和PDI均呈下降趋势,是因为悬浮液pH影响了硅溶胶的溶解平衡;而固态二氧化硅悬浮液的粒径和PDI则呈先上升后下降的趋势,这是由于悬浮液pH影响了双电层结构.实际测试和应用中应注意悬浮液配制条件和纳米二氧化硅类别对粒径和PDI的影响.

研究了一种用于油田开发的新型荧光纳米示踪剂的性能,该示踪剂由亲水层-隔离层-荧光物质三层核壳结构构成.研究结果表明:该示踪剂具有较宽的检测范围(5×10-3～0.5 mg·L-1)和较高的检测精度(10-9数量级);在矿化度105 mg·L-1、二价离子质量浓度500 mg·L-1、pH值5～9、温度75℃以内具有较小的测量误差;由于示踪剂亲水层的特性,该示踪剂在石英砂表面吸附率仅为5％,静态吸附量为0.25μg·g-1,且在油相中基本不溶解.因此该类型示踪剂具有油藏条件适应性好、成本低廉、施工简单、检测便利快速等特点,可实现示踪剂浓度的在线快速检测分析.

为准确认识江汉油田硬石膏胶结的低渗透砂岩油藏压裂过程中水敏性伤害的原因,结合储层地质资料,并通过原位扫描电镜、X射线衍射、薄片分析等方法对目标油藏进行储层伤害微观机理研究.结果表明:储层中作为胶结物的硬石膏导致的水化膨胀和溶解再沉淀,砂粒脱落是引起压裂过程中水敏伤害的主要原因.因此可以在压裂液中加入合适的阻垢剂,防治石膏引起的储层伤害问题.

对国内外Fe3O4磁性纳米颗粒的表面改性方法及其油气田开发领域应用现状进行了系统调研,按照其表面功能化改性材料划分为无机材料改性、有机小分子材料改性、有机高分子材料改性.功能化改性后Fe3 O4磁性纳米颗粒在油气田开发领域中应用时包括在提高采收率、污水处理、石油机械保护等方面,具有良好的应用前景.并对其在油气田开发领域应用发展进行了展望,指出开发出具备特异性功能的磁性纳米颗粒,进一步改善其表面性质、负载功能基团的吸附量和稳定性,降低生产成本是该领域的主要研究方向.

对国内外现有主要除硼技术的原理及其应用现状进行了系统调研,如化学沉淀法、膜分离法、吸附法等,并分析将其应用于压裂返排液中残余硼处理上的可行性.综合考虑压裂返排液回用技术经济指标的要求,认为吸附法较为适合处理压裂返排液中残余硼,而有效改善现有硼吸附剂的可再生性、提高官能团的负载率是该领域的主要研究方向.